Tokyo, Japan - The US is reportedly drawing up contingency plans for military deployments in Japan and the Philippines to counter China in case of an emergency over Taiwan.

The considerations will be incorporated in a first joint operation plan to be formulated in December, Japan's Kyodo news agency reported late Sunday, citing sources familiar with Japan-US relations.

A US Marine regiment which possesses the multiple-launch HIMARS (High Mobility Artillery Rocket System) would be deployed along Japan's Nansei island chain stretching from Kyushu to Yonaguni near Taiwan, Kyodo said.

From an early stage, if a Taiwan contingency becomes highly imminent, temporary bases will be set up on inhabited islands based on US military guidelines for dispatching marines in small formations to several locations, the report added.

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Japan's military would be expected to mainly engage in logistical support for the marine unit, including supplying fuel and ammunition.

Kyodo added that the US Army would deploy Multi-Domain Task Force long-range fire units in the Philippines.

The Japanese and Philippines defense ministries were not immediately available for comment, while the US embassy in Manila declined to respond.

Asked about the report on Monday, Beijing's foreign ministry said that Taiwan is an "inalienable part of China's territory".

"China firmly opposes relevant countries using the Taiwan issue as an excuse to strengthen regional military deployment, provoke tension and confrontation, and damage regional peace and stability," foreign ministry spokesperson Mao Ning said.

The US has been strengthening alliances in the region, while infuriating Beijing with regular deployments of ships and fighter jets in the Taiwan Strait and the South China Sea, where tensions are worsening.